凝血酶調節素為一穿膜醣蛋白，在內皮細胞、單核球細胞以及巨噬細胞中均有表現。文獻指出，具有多功能的凝血酶調節素除了參與發炎反應外，還有調控細胞彼此間黏附的功能。腹主動脈瘤是由於主動脈逐漸膨脹導致管壁變薄弱而容易破裂的系統性心血管疾病，被視為是一種血管發炎的疾病。它的成因與動脈管壁的結締組織結構變化有密切關係，包括細胞外基質的受損、動脈血管壁中層組成成份平滑肌細胞的減少，以及免疫細胞在病灶處積聚，其中又以巨噬細胞的浸潤最為明顯。當巨噬細胞浸潤組織後，會引起一連串的發炎前驅物質增加並且活化蛋白水解酶，使得血管管壁組織發生劇烈變化。不過至今，單核球細胞上之凝血酶調節素在腹主動脈瘤形成時所扮演的角色尚未清楚。本論文利用特異骨髓凝血酶調節素剔除小鼠(LysMcre/TMflox/floxmice)，探討單核球細胞上之凝血酶調節素是否與腹主動脈瘤的形成相關。結果顯示，巨噬細胞缺乏凝血酶調節素之小鼠在經由第二型血管收縮素引起的腹主動脈瘤後，不論是主動脈膨脹的情形、巨噬細胞浸潤的程度以及發炎前驅物質的增加量皆有減緩的趨勢。為了找出明確的機制，我們以腹腔注射硫乙醇酸於小鼠4天後，自腹水分離出巨噬細胞後觀察到，凝血酶調節素在由硫乙醇酸活化的巨噬細胞中表現量增加，顯示凝血酶調節素可能與巨噬細胞的成熟或活化息息相關。我們亦發現，不論是利用基因剔除凝血酶調節素或是加入凝血酶調節素的抗體，都能有效地減少單核球及巨噬細胞與內皮細胞彼此間的黏附現象。除此之外，缺乏凝血酶調節素的巨噬細胞，發炎前驅物質以及基質金屬蛋白酶之表現量皆下降。綜合以上結果，單核球及巨噬細胞上的凝血酶調節素，可能是藉由調控與內皮細胞的黏附及影響前發炎物質以及基質金屬蛋白酶的生成，進而促進腹主動脈瘤的形成。在未來，針對凝血酶調節素所調控的單核球及巨噬細胞之拮抗劑可能開發成治療腹主動脈瘤的新標靶藥物。

Thrombomodulin (TM) is a transmembrane glycoprotein widely expressed on many cell types, such as endothelial cells and monocytes/macrophages. Recent studies have shown that TM is a multi-functional molecule participated in inflammation and cellular adhesion. Abdominal aortic aneurysm (AAA) is a degenerative disease of the abdominal aorta which results in a weakened and systemic dilated aorta that is prone to rupture. AAA has been classified as an inflammatory vascular disease and typically characterized by destruction of extracellular matrix, loss of smooth muscle cells in the media, and accumulation of inflammatory cells in lesions. The most important pathogenesis is transmural infiltration of inflammatory cells, including macrophages, which play a pivotal role through release of a cascade of proinflammatory mediators and proteolytic enzymes. Up to now, the role of monocytic TM in AAA formation remains unclear. In this study, to explore whether the monocytic TM modulates AAA formation, we used myeloid-specific TM-deficient mice (LysMcre/TMflox/flox mice). The results showed that TM-deficient mice had reduced aortic expansion, macrophage infiltration, and levels of proinflammatory mediators in the AAA lesion induced by angiotensin II. To pursue the possible mechanism by which monocytic TM participated in AAA formation, inflammatory macrophages were isolated from peritoneal lavages at 4 days after thioglycollate (TG) injection. We found that TM expression was elevated in TG-induced macrophages compared with non-induced resident peritoneal macrophages, suggesting that increased expression of TM might be associated with maturation of inflammatory macrophages. Moreover, genetic deletion or antibody blockade of TM led to reduced monocytes/macrophages adhesion to endothelial cells. In addition, not only proinflammatory mediators but also matrix metalloproteinase 9 in TG-induced TM-deficient macrophages were significantly decreased. In conclusion, our results demonstrate that monocytic TM may contribute to AAA development via modulation of monocyte/macrophage adhesion and proinflammatory mediator secretion. These findings suggest targeting of TM-mediated pathways in monocytes/macrophages might provide a new therapeutic strategy to antagonize AAA progression.

1. Hans, C. P., Koenig, S. N., Huang, N., Cheng, J., Beceiro, S., Guggilam, A., Kuivaniemi, H., Partida-Sanchez, S., and Garg, V. (2012) Inhibition of Notch1 signaling reduces abdominal aortic aneurysm in mice by attenuating macrophage-mediated inflammation. Arteriosclerosis, thrombosis, and vascular biology 32, 3012-3023
2. Blanchard, J. F., Armenian, H. K., and Friesen, P. P. (2000) Risk factors for abdominal aortic aneurysm: results of a case-control study. American journal of epidemiology 151, 575-583
3. Tazume, H., Miyata, K., Tian, Z., Endo, M., Horiguchi, H., Takahashi, O., Horio, E., Tsukano, H., Kadomatsu, T., Nakashima, Y., Kunitomo, R., Kaneko, Y., Moriyama, S., Sakaguchi, H., Okamoto, K., Hara, M., Yoshinaga, T., Yoshimura, K., Aoki, H., Araki, K., Hao, H., Kawasuji, M., and Oike, Y. (2012) Macrophage-derived angiopoietin-like protein 2 accelerates development of abdominal aortic aneurysm. Arteriosclerosis, thrombosis, and vascular biology 32, 1400-1409
4. Kniemeyer, H. W., Kessler, T., Reber, P. U., Ris, H. B., Hakki, H., and Widmer, M. K. (2000) Treatment of ruptured abdominal aortic aneurysm, a permanent challenge or a waste of resources? Prediction of outcome using a multi-organ-dysfunction score. European journal of vascular and endovascular surgery : the official journal of the European Society for Vascular Surgery 19, 190-196
5. Brewster, D. C., Cronenwett, J. L., Hallett, J. W., Jr., Johnston, K. W., Krupski, W. C., Matsumura, J. S., Joint Council of the American Association for Vascular, S., and Society for Vascular, S. (2003) Guidelines for the treatment of abdominal aortic aneurysms. Report of a subcommittee of the Joint Council of the American Association for Vascular Surgery and Society for Vascular Surgery. Journal of vascular surgery 37, 1106-1117
6. Shimizu, K., Mitchell, R. N., and Libby, P. (2006) Inflammation and cellular immune responses in abdominal aortic aneurysms. Arteriosclerosis, thrombosis, and vascular biology 26, 987-994
7. Koch, A. E., Haines, G. K., Rizzo, R. J., Radosevich, J. A., Pope, R. M., Robinson, P. G., and Pearce, W. H. (1990) Human abdominal aortic aneurysms. Immunophenotypic analysis suggesting an immune-mediated response. The American journal of pathology 137, 1199-1213
8. Enzerink, A., and Vaheri, A. (2011) Fibroblast activation in vascular inflammation. Journal of thrombosis and haemostasis : JTH 9, 619-626
9. Samadzadeh, K. M., Chun, K. C., Nguyen, A. T., Baker, P. M., Bains, S., and Lee, E. S. (2014) Monocyte activity is linked with abdominal aortic aneurysm diameter. The Journal of surgical research
10. Kaneko, H., Anzai, T., Takahashi, T., Kohno, T., Shimoda, M., Sasaki, A., Shimizu, H., Nagai, T., Maekawa, Y., Yoshimura, K., Aoki, H., Yoshikawa, T., Okada, Y., Yozu, R., Ogawa, S., and Fukuda, K. (2011) Role of vascular endothelial growth factor-A in development of abdominal aortic aneurysm. Cardiovascular research 91, 358-367
11. Xiong, W., MacTaggart, J., Knispel, R., Worth, J., Persidsky, Y., and Baxter, B. T. (2009) Blocking TNF-alpha attenuates aneurysm formation in a murine model. Journal of immunology 183, 2741-2746
12. Keeling, W. B. (2005) An Overview of Matrix Metalloproteinases in the Pathogenesis and Treatment of Abdominal Aortic Aneurysms. Vascular and Endovascular Surgery 39, 457-464
13. Thompson, R. W., Holmes, D. R., Mertens, R. A., Liao, S., Botney, M. D., Mecham, R. P., Welgus, H. G., and Parks, W. C. (1995) Production and localization of 92-kilodalton gelatinase in abdominal aortic aneurysms. An elastolytic metalloproteinase expressed by aneurysm-infiltrating macrophages. The Journal of clinical investigation 96, 318-326
14. Xiong, W., Mactaggart, J., Knispel, R., Worth, J., Zhu, Z., Li, Y., Sun, Y., Baxter, B. T., and Johanning, J. (2009) Inhibition of reactive oxygen species attenuates aneurysm formation in a murine model. Atherosclerosis 202, 128-134
15. Lum, H., and Roebuck, K. A. (2001) Oxidant stress and endothelial cell dysfunction. American journal of physiology. Cell physiology 280, C719-741
16. Lee, C. F., Ullevig, S., Kim, H. S., and Asmis, R. (2013) Regulation of Monocyte Adhesion and Migration by Nox4. PloS one 8, e66964
17. Marumo, T., Schini-Kerth, V. B., Fisslthaler, B., and Busse, R. (1997) Platelet-derived growth factor-stimulated superoxide anion production modulates activation of transcription factor NF-kappaB and expression of monocyte chemoattractant protein 1 in human aortic smooth muscle cells. Circulation 96, 2361-2367
18. Rajagopalan, S., Meng, X. P., Ramasamy, S., Harrison, D. G., and Galis, Z. S. (1996) Reactive oxygen species produced by macrophage-derived foam cells regulate the activity of vascular matrix metalloproteinases in vitro. Implications for atherosclerotic plaque stability. The Journal of clinical investigation 98, 2572-2579
19. Suzuki, K., Kusumoto, H., Deyashiki, Y., Nishioka, J., Maruyama, I., Zushi, M., Kawahara, S., Honda, G., Yamamoto, S., and Horiguchi, S. (1987) Structure and expression of human thrombomodulin, a thrombin receptor on endothelium acting as a cofactor for protein C activation. The EMBO journal 6, 1891-1897
20. Tracy, P. B. (1988) Regulation of thrombin generation at cell surfaces. Seminars in thrombosis and hemostasis 14, 227-233
21. Owen, W. G., and Esmon, C. T. (1981) Functional properties of an endothelial cell cofactor for thrombin-catalyzed activation of protein C. The Journal of biological chemistry 256, 5532-5535
22. Esmon, C. T. (1989) The roles of protein C and thrombomodulin in the regulation of blood coagulation. The Journal of biological chemistry 264, 4743-4746
23. Mizutani, H., Hayashi, T., Nouchi, N., Ohyanagi, S., Hashimoto, K., Shimizu, M., and Suzuki, K. (1994) Functional and immunoreactive thrombomodulin expressed by keratinocytes. The Journal of investigative dermatology 103, 825-828
24. Maruyama, I., Bell, C. E., and Majerus, P. W. (1985) Thrombomodulin is found on endothelium of arteries, veins, capillaries, and lymphatics, and on syncytiotrophoblast of human placenta. The Journal of cell biology 101, 363-371
25. McCachren, S. S., Diggs, J., Weinberg, J. B., and Dittman, W. A. (1991) Thrombomodulin expression by human blood monocytes and by human synovial tissue lining macrophages. Blood 78, 3128-3132
26. Conway, E. M., Nowakowski, B., and Steiner-Mosonyi, M. (1992) Human neutrophils synthesize thrombomodulin that does not promote thrombin-dependent protein C activation. Blood 80, 1254-1263
27. Bretschneider, E., Uzonyi, B., Weber, A. A., Fischer, J. W., Pape, R., Lotzer, K., and Schror, K. (2007) Human vascular smooth muscle cells express functionally active endothelial cell protein C receptor. Circulation research 100, 255-262
28. Healy, A. M., Rayburn, H. B., Rosenberg, R. D., and Weiler, H. (1995) Absence of the blood-clotting regulator thrombomodulin causes embryonic lethality in mice before development of a functional cardiovascular system. Proceedings of the National Academy of Sciences of the United States of America 92, 850-854
29. Shi, C. S., Shi, G. Y., Chang, Y. S., Han, H. S., Kuo, C. H., Liu, C., Huang, H. C., Chang, Y. J., Chen, P. S., and Wu, H. L. (2005) Evidence of human thrombomodulin domain as a novel angiogenic factor. Circulation 111, 1627-1636
30. Huang, H. C., Shi, G. Y., Jiang, S. J., Shi, C. S., Wu, C. M., Yang, H. Y., and Wu, H. L. (2003) Thrombomodulin-mediated cell adhesion: involvement of its lectin-like domain. The Journal of biological chemistry 278, 46750-46759
31. Son, B. K., Akishita, M., Iijima, K., Ogawa, S., Arai, T., Ishii, H., Maemura, K., Aburatani, H., Eto, M., and Ouchi, Y. (2013) Thrombomodulin, a novel molecule regulating inorganic phosphate-induced vascular smooth muscle cell calcification. Journal of molecular and cellular cardiology 56, 72-80
32. Kao, Y. C., Wu, L. W., Shi, C. S., Chu, C. H., Huang, C. W., Kuo, C. P., Sheu, H. M., Shi, G. Y., and Wu, H. L. (2010) Downregulation of thrombomodulin, a novel target of Snail, induces tumorigenesis through epithelial-mesenchymal transition. Molecular and cellular biology 30, 4767-4785
33. Van de Wouwer, M., and Conway, E. M. (2004) Novel functions of thrombomodulin in inflammation. Critical Care Medicine 32, S254-S261
34. Riewald, M., Petrovan, R. J., Donner, A., Mueller, B. M., and Ruf, W. (2002) Activation of endothelial cell protease activated receptor 1 by the protein C pathway. Science 296, 1880-1882
35. Grinnell, B. W., Hermann, R. B., and Yan, S. B. (1994) Human protein C inhibits selectin-mediated cell adhesion: role of unique fucosylated oligosaccharide. Glycobiology 4, 221-225
36. Abeyama, K., Stern, D. M., Ito, Y., Kawahara, K.-i., Yoshimoto, Y., Tanaka, M., Uchimura, T., Ida, N., Yamazaki, Y., Yamada, S., Yamamoto, Y., Yamamoto, H., Iino, S., Taniguchi, N., and Maruyama, I. (2005) The N-terminal domain of thrombomodulin sequesters high-mobility group-B1 protein, a novel antiinflammatory mechanism. Journal of Clinical Investigation 115, 1267-1274
37. Shi, C. S., Shi, G. Y., Hsiao, H. M., Kao, Y. C., Kuo, K. L., Ma, C. Y., Kuo, C. H., Chang, B. I., Chang, C. F., Lin, C. H., Wong, C. H., and Wu, H. L. (2008) Lectin-like domain of thrombomodulin binds to its specific ligand Lewis Y antigen and neutralizes lipopolysaccharide-induced inflammatory response. Blood 112, 3661-3670
38. Conway, E. M., Van de Wouwer, M., Pollefeyt, S., Jurk, K., Van Aken, H., De Vriese, A., Weitz, J. I., Weiler, H., Hellings, P. W., Schaeffer, P., Herbert, J. M., Collen, D., and Theilmeier, G. (2002) The Lectin-like Domain of Thrombomodulin Confers Protection from Neutrophil-mediated Tissue Damage by Suppressing Adhesion Molecule Expression via Nuclear Factor B and Mitogen-activated Protein Kinase Pathways. Journal of Experimental Medicine 196, 565-577
39. Lin, W. L., Chang, C. F., Shi, C. S., Shi, G. Y., and Wu, H. L. (2013) Recombinant lectin-like domain of thrombomodulin suppresses vascular inflammation by reducing leukocyte recruitment via interacting with Lewis Y on endothelial cells. Arteriosclerosis, thrombosis, and vascular biology 33, 2366-2373
40. Ma, C. Y., Shi, G. Y., Shi, C. S., Kao, Y. C., Lin, S. W., and Wu, H. L. (2012) Monocytic thrombomodulin triggers LPS- and gram-negative bacteria-induced inflammatory response. Journal of immunology 188, 6328-6337
41. Thompson, M. M., Jones, L., Nasim, A., Sayers, R. D., and Bell, P. R. (1996) Angiogenesis in abdominal aortic aneurysms. European journal of vascular and endovascular surgery : the official journal of the European Society for Vascular Surgery 11, 464-469
42. McHale, J. F., Harari, O. A., Marshall, D., and Haskard, D. O. (1999) Vascular endothelial cell expression of ICAM-1 and VCAM-1 at the onset of eliciting contact hypersensitivity in mice: evidence for a dominant role of TNF-alpha. Journal of immunology 162, 1648-1655
43. Anidjar, S., Dobrin, P. B., Eichorst, M., Graham, G. P., and Chejfec, G. (1992) Correlation of inflammatory infiltrate with the enlargement of experimental aortic aneurysms. Journal of vascular surgery 16, 139-147
44. Ma, B. Y., Kaihama, M., Nonaka, M., Oka, S., Kawasaki, N., and Kawasaki, T. (2007) LPS suppresses expression of asialoglycoprotein-binding protein through TLR4 in thioglycolate-elicited peritoneal macrophages. Glycoconjugate journal 24, 243-249
45. Kadoglou, N. P., and Liapis, C. D. (2004) Matrix metalloproteinases: contribution to pathogenesis, diagnosis, surveillance and treatment of abdominal aortic aneurysms. Current medical research and opinion 20, 419-432
46. Quiding-Jarbrink, M., Smith, D. A., and Bancroft, G. J. (2001) Production of matrix metalloproteinases in response to mycobacterial infection. Infection and immunity 69, 5661-5670
47. Heidinger, M., Kolb, H., Krell, H. W., Jochum, M., and Ries, C. (2006) Modulation of autocrine TNF-alpha-stimulated matrix metalloproteinase 9 (MMP-9) expression by mitogen-activated protein kinases in THP-1 monocytic cells. Biological chemistry 387, 69-78
48. Tsai, C. L., Chen, W. C., Hsieh, H. L., Chi, P. L., Hsiao, L. D., and Yang, C. M. (2014) TNF-alpha induces matrix metalloproteinase-9-dependent soluble intercellular adhesion molecule-1 release via TRAF2-mediated MAPKs and NF-kappaB activation in osteoblast-like MC3T3-E1 cells. Journal of biomedical science 21, 12
49. Tieu, B. C., Lee, C., Sun, H., Lejeune, W., Recinos, A., 3rd, Ju, X., Spratt, H., Guo, D. C., Milewicz, D., Tilton, R. G., and Brasier, A. R. (2009) An adventitial IL-6/MCP1 amplification loop accelerates macrophage-mediated vascular inflammation leading to aortic dissection in mice. The Journal of clinical investigation 119, 3637-3651
50. Tieu, B. C., Ju, X., Lee, C., Sun, H., Lejeune, W., Recinos, A., 3rd, Brasier, A. R., and Tilton, R. G. (2011) Aortic adventitial fibroblasts participate in angiotensin-induced vascular wall inflammation and remodeling. Journal of vascular research 48, 261-272
51. Park, H. S., Jung, H. Y., Park, E. Y., Kim, J., Lee, W. J., and Bae, Y. S. (2004) Cutting edge: direct interaction of TLR4 with NAD(P)H oxidase 4 isozyme is essential for lipopolysaccharide-induced production of reactive oxygen species and activation of NF-kappa B. Journal of immunology 173, 3589-3593
52. Tewari, R., Choudhury, S. R., Ghosh, S., Mehta, V. S., and Sen, E. (2012) Involvement of TNFalpha-induced TLR4-NF-kappaB and TLR4-HIF-1alpha feed-forward loops in the regulation of inflammatory responses in glioma. Journal of molecular medicine 90, 67-80
53. Marinkovic, G., Hibender, S., Hoogenboezem, M., van Broekhoven, A., Girigorie, A. F., Bleeker, N., Hamers, A. A., Stap, J., van Buul, J. D., de Vries, C. J., and de Waard, V. (2013) Immunosuppressive drug azathioprine reduces aneurysm progression through inhibition of Rac1 and c-Jun-terminal-N-kinase in endothelial cells. Arteriosclerosis, thrombosis, and vascular biology 33, 2380-2388
54. Ito, T., and Maruyama, I. (2011) Thrombomodulin: protectorate God of the vasculature in thrombosis and inflammation. Journal of thrombosis and haemostasis : JTH 9 Suppl 1, 168-173